OS X compile fixes

some basic work for #7.

There is a also a bunch of system setup that needs to be done... but that is best worked around with hackery at the moment because it involves changing so much code (specifically the location of the `cl.h` file is not under `CL/cl.h`, it's in the frameworks directory, `malloc.h` is in `malloc/malloc.h`  and I have no idea what the OS X `#define` logic is looking for... you should be looking for `MACH`)

```
sudo port install boost gcc-4.8
mkdir build
cd build
ln -s /System/Library/Frameworks/OpenCL.framework/Headers/ ../src/include/CL
ln -s /usr/include/malloc/malloc.h ../src/include/malloc.h
#CC=gcc-mp-4.8 CXX=g++-mp-4.8 LDFLAGS="-framework OpenCL" cmake ../src
LDFLAGS="-framework OpenCL" cmake ../src
make
```